Process and device for the treatment of atrial arrhythmia

ABSTRACT

A process for the treatment of atrial arrhythmia by use of ablation procedures comprising circumferential ablation of vessels, particularly pulmonary veins, associated with the left atrium of the heart. Also medical devices for such process including a pair of balloons secured to a catheter with one balloon located within the other balloon and an ablation catheter located within one of the balloons, which devices are used for the formation of a circumferential ablation lesion in the pulmonary vein.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part application based onapplication Ser. No. 08/883,668, filed Jun. 27, 1997.

BACKGROUND OF INVENTION

[0002] This invention relates to medical devices and processes usefulfor the treatment of atrial arrhythmia. In particular, it relates to apreferred process and medical device used for ablation procedures invessels of the human body, namely the pulmonary veins.

[0003] Introducers and catheters have been in use for medical proceduresfor many years. For example, one procedure utilizes a catheter to conveyan electrical stimulus to a selected location within the human body.Another procedure utilizes a catheter to monitor activity in variouslocations in the body for diagnostic tests. Thus, catheters may examine,diagnose and treat while positioned at specific locations within thebody which are otherwise inaccessible without more invasive procedures.In use, catheters may be inserted into a major vein or artery which isnear the body surface. These catheters are then guided to a specificlocation for examination, diagnosis and treatment by manipulating thecatheter through the artery or vein of the human body, frequently withthe assistance of other medical devices, such as introducers orguidewires.

[0004] One common medical procedure utilizing specialized catheters isthe treatment of vessels located within the human body, frequentlyvessels associated with the human heart. Those procedures, most notablyangioplasty procedures, utilize a catheter which often contains aninflatable balloon secured to the catheter. In some of these medicalprocedures, the catheter contains a pair of inflatable balloons used tolimit the portion of the vessel that is treated or to assure that thecatheter remains at a fixed location within the vessel throughout themedical procedure or to assist in the performance of the medicalprocedure.

[0005] Multiple balloon catheters are utilized throughout the body. Forexample, U.S. Pat. No. 5,468,239 discloses a device for circumferentiallaser burning of tissue in a urethral canal. This device utilizes a pairof cuffs or balloons (60) with a laser probe (12) located between thoseballoons. U.S. Pat. No. 5,588,961 discloses an infusion catheter fordelivery of medication to a vessel and contains a pair of balloons (16,17) and an electrode (35) secured to the catheter. Ports are provided inthe catheter to introduce the medication into the space between the twoballoons within the vessel. Energy may also be introduced into theelectrode to encourage the movement of the medication away from thecatheter toward the walls of the vessel. U.S. Pat. No. 5,256,141discloses a pair of balloons (14, 18) with an electrode secured to acatheter to apply a controlled electric charge to material introducedinto the space in the vessel between the two balloons.

[0006] Biological material may also be introduced into this space formedical treatment of the vessel. U.S. Pat. No. 5,366,490 discloses apair of balloons (30, 32) secured to a catheter and a stylette (36).Radio frequency energy is supplied to the catheter to destroy tissue.U.S. Pat. No. 5,599,307 discloses a pair of balloons (41, 42) secured toa catheter designed to occlude a vessel. U.S. Pat. No. 5,002,532discloses a pair of balloons (21, 22) secured to a catheter (12) for usein a dilation procedure within a vessel, whereby the two balloons may beinflated to different extents. U.S. Pat. No. 5,792,105 discloses amultichannel balloon catheter for delivering fluids which utilizes aninner and an outer balloons. See also U.S. Pat. No. 4,445,892.

[0007] In addition to the use of multiple balloons on a single catheterfor medical procedures, U.S. Pat. No. 5,462,529 discloses a medicaldevice containing a pair of catheters (12, 28), each containing aballoon (20, 48) secured at or near its distal end, which device isutilized to perform a medical procedure within a vessel. U.S. Pat. No.5,484,412 also discloses a pair of catheters (18, 22) utilized toperform a medical procedure within a vessel, each containing aninflatable balloon (36, 38). U.S. Pat. No. 4,911,163 discloses a pair ofballoons (2, 8) secured to a pair of catheters (1, 7) for introductionof medicine or diagnostic fluids into the space between the twoballoons.

[0008] Atrial fibrillation is the most common sustained heartarrhythmia. It is estimated to occur in upwards of 0.4 percent of theadult population and perhaps as many as 10 percent of the population whoare 60 years or older. Cox, J. L., et al., Electrophysiology, Pacing andArrhythmia, “Operations for Atrial Fibrillation,” Clin. Cardiol. 14,827-834 (1991).

[0009] Atrial arrhythmia may be transient or persistent. While mostatrial arrhythmia occur in individuals having other forms of underlyingheart disease, some atrial arrhythmia occur independently. While atrialarrhythmia do not directly cause death as frequently as ventriculararrhythmia, they increase the risk factors for a number of otherdiseases such as systemic and cerebral embolism and may cause a numberof additional medical problems.

[0010] In the treatment of atrial arrhythmia, antiarrhythmic drugssometimes provide relief. Other treatments for atrial arrhythmia orfibrillation involve the use of an implanted atrial defibrillator orcardioversion. See, for example, U.S. Pat. Nos. 5,282,836, 5,271,392 and5,209,229 and Martin, D., et al., Atrial Fibrillation, pgs. 42-59(1994).

[0011] Certain patients with symptomatic or life threatening atrialarrhythmia, however, cannot be adequately treated by drugs or thesetypes of medical devices. Other forms of aggressive treatment aresometimes mandated, which have in the past included surgery. Forexample, a surgical procedure for the treatment of atrial arrhythmiaknown as the “Maze” procedure is discussed in Cox, J. L. et al.,Electrophysiology, Pacing and Arrhythmia, “Operations for AtrialFibrillation,” Clin. Cardiol. Vol. 14, pgs. 827-834 (1991).

[0012] Another procedure increasingly used within the last 10 to 15years for the treatment of certain types of cardiac arrhythmia involvesablation of cardiac tissue. For example, this procedure has beencommonly used to interrupt or modify existing conduction pathwaysassociated with arrhythmia within the heart. The particular area forablation depends on the type of underlying arrhythmia. The use of radiofrequency catheter ablation for the treatment of paroxysmal atrialfibrillation is disclosed in Haissaguerre, M., et al., “Right and LeftAtrial Radiofrequency Catheter Therapy of Paroxysmal AtrialFibrillation” J. Cardiovascular Electrophysiology, V.7, pgs. 1132-1144(December 1996). Ablation procedures have also been used for thetreatment of atrioventricular (AV) nodal reentrant tachycardia. Withthis condition, ablation of the fast or slow AV nodal pathways hasbecome an accepted treatment. Singer, I., et al., “Catheter Ablation forArrhythmias” Clinical Manual of Electrophysiology, pgs. 421-431 (1993);Falk, R. H., et al., Atrial Fibrillation Mechanisms in Management, pgs.359-374 (1992); Horowitz, L. N., Current Management of Arrhythmias, pgs.373-378 (1991); and Martin, D., et al., Atrial Fibrillation, pgs. 42-59(1994). In addition, the use of ablation catheters for ablatinglocations within the heart has been disclosed, for example in U.S. Pat.Nos. 4,641,649, 5,263,493, 5,231,995, 5,228,442 and 5,281,217.

[0013] The sources of energy used for catheter ablation vary. Initially,high voltage, direct current (DC) ablation techniques were commonlyused. However, because of problems associated with the use of DCcurrent, radio frequency (Rf) energy has become the preferred source ofenergy for ablation procedures. The use of Rf energy for ablation hasbeen disclosed, for example, in U.S. Pat. Nos. 4,945,912, 5,209,229,5,281,218, 5,242,441, 5,246,438, 5,281,213 and 5,293,868. Other energysources which are being used currently or are being considered forablation of heart tissue include laser, ultrasound, microwave andfulgutronization.

[0014] Ablation of a precise location within the heart requires theprecise placement of the ablation catheter within the heart. Precisepositioning of the ablation catheter is especially difficult because ofthe physiology of the heart, particularly as the ablation proceduresgenerally occur while the heart is beating. Commonly, the placement ofthe catheter is determined by a combination of electrophysiologicalguidance and fluoroscopy (placement of the catheter in relation to knownfeatures of the heart which are marked by radiopaque diagnosticcatheters which are placed in or at known anatomical structures such asthe coronary sinus, high right atrium and the right ventricle).

[0015] A process for the mapping and treatment of atrial arrhythmiausing ablation catheters guided to a specific location by shaped,guiding introducers is disclosed in U.S. Pat. Nos. 5,427,119, 5,497,774,5,575,766, 5,564,440, 5,628,316 and 5,640,955. In particular, a processfor the ablation of defined tracks within the left and/or right atriumas an element of the treatment of atrial fibrillation is disclosed inU.S. Pat. No. 5,575,766.

[0016] The mechanism for initiation of some forms of atrial arrhythmia,such as atrial premature contractions, is not well understood. As aresult, ablation procedures in the heart have focused on the formationof lesions within the chambers of the heart at selected locations whicheither prevent the passage of electrical signals associated with atrialpremature contractions or prevent the formation of improper electricalpathways within the heart, which can result in atrial arrhythmia.

[0017] It has been surprisingly discovered that one source for theseatrial premature contractions originates within vessels associated withthe heart, in particular the pulmonary veins. Once these atrialpremature contractions form in the pulmonary veins, they areperiodically conducted into the left atrium. When the atrial prematurecontractions enter the left atrium, they can initiate or continue anepisode of atrial fibrillation.

[0018] Invasive treatment of atrial fibrillation in the past around thepulmonary veins has been limited to the formation of lesions in the leftatrium created by an invasive surgical procedure, such as is disclosedby Cox, J. L., et al., Electrophysiology, Pacing and Arrhythmia,“Operations for Atrial Fibrillation” Clin. Cardiol. Vol. 14, pgs.827-834 (1991). In addition, the use of precurved guiding introducers toguide ablation catheters to appropriate locations in the left atrium foruse in the formation of lesions around the pulmonary veins has beendisclosed in U.S. Pat. No. 5,575,766.

[0019] While these procedures have been successful in some patients,other patients require additional treatment as the treatments previouslydisclosed have not been completely successful in the elimination of theatrial fibrillation. In addition, these ablation procedures can be verytime consuming, requiring as long as 10-15 hours.

[0020] It is therefore an aspect of this invention to disclose a medicaldevice useful in the treatment of atrial arrhythmia, particularly atrialfibrillation.

[0021] It is an additional aspect of this invention to disclose amedical device useful for the formation of ablation lesions in vesselsin the body.

[0022] It is a still further aspect of this invention to disclose amedical device containing a pair of inflatable balloons, one locatedinside of the other, and an ablation electrode, which components areutilized to form a circumferential ablation lesion for the treatment ofatrial arrhythmia, particularly atrial premature contractions.

[0023] It is a still further aspect of this invention to disclose aprocess for the formation of circumferential ablation lesions in vesselsin the human body.

[0024] It is a still further aspect of this invention to disclose aprocess for ablation of tissue located within the pulmonary veins, or onthe os of the pulmonary veins.

[0025] It is a still further aspect of this invention to disclose aprocess for the formation of circumferential lesions in the pulmonaryveins, or on the os of the pulmonary veins.

[0026] It is a still further aspect of this invention to disclosemedical procedures for the production of circumferential ablationlesions within vessels of the heart, or on the os of those vessels, forthe treatment of atrial fibrillation.

[0027] It is a still further aspect of this invention to disclose aprocess for the formation of ablation lesions within a vessel of theheart, or on the os of that vessel, using Rf energy.

[0028] These and other aspects of the invention are disclosed by theprocesses for the treatment of atrial arrhythmia and the design of themedical products for use with those processes.

SUMMARY OF INVENTION

[0029] The present invention is an ablation catheter useful for ablationprocedures within a vessel of a human, or on the os of that vessel,particularly a pulmonary vein. A first and a second balloon are securedto the catheter, with the second balloon secured to the catheter andlocated inside the first balloon. The balloons, when inflated, seal thevessel and prevent substantially the flow of blood through the vesselaround these balloons. An introduction system is also included as anelement of the ablation catheter to introduce a conductive media to thespace within the first and second balloons when inflated. The firstballoon contains a plurality of balloon openings in its outside surfacethrough which the conductive media is expelled to contact the tissue ofthe vessel. An ablating system is also included as an element of theablation catheter, which system is secured to the catheter at a locationwithin the first, outer balloon, but outside of the second, innerballoon. The ablating system includes one or more Rf energy ablationelectrodes, which may be in the form of a coil electrode or a ringelectrode. The conductive media conducts the ablating energy from theablating system out through the balloon openings in that first balloonto contact the tissue located in the vessel, or on the os of the vessel,adjacent to the balloon openings to form a circumferential ablationlesion in the vessel or on the os of the vessel.

[0030] Alternatively, the present invention is a medical device forablation within a vessel of a human, or on the os of that vessel, andincludes the catheter system discussed above used in conjunction with ashaped guiding introducer with a proximal and distal end and a lumenpassing from its proximal to its distal end. The shaped introducerguides the ablation catheter to the desired location in the vessel, oron the Os of that vessel, to perform the ablation procedure.

[0031] Also disclosed is a process for the ablation of tissue within avessel of a human, particularly a pulmonary vein, which includesintroducing an ablation catheter containing a first, and a secondballoon and an electrode into the vessel, or on the os of the vessel,wherein the second balloon is located within the first balloon, sealingthe vessel to prevent substantially the flow of blood through the vesselusing the first and second balloons, passing conductive media fromwithin the first balloon through a plurality of balloon openings in thesurface of the first balloon and conducting energy from the ablationelectrode by use of the conductive media to contact the tissue withinthe vessel, or the os of the vessels, resulting in the formation of acircumferential ablation lesion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a cut away view of the heart showing the left atrium andthe four pulmonary veins.

[0033]FIG. 2 is a cut away view of the left atrium showing the ablationcatheter of the present invention being introduced into one of thepulmonary veins.

[0034]FIG. 2A is a cut away view of the ablation catheter of the presentinvention being introduced into one of the pulmonary veins.

[0035]FIG. 3 is a perspective view of the ablation catheter of thepresent invention with the balloons not inflated.

[0036]FIG. 4 is a perspective view of a distal portion of the ablationcatheter of FIG. 3 with the balloons not inflated.

[0037]FIG. 5 is a cut away, perspective view of the ablation catheter ofFIG. 3 with the balloons inflated.

[0038]FIG. 6 is a cutaway, perspective view of a distal portion of theablation catheter of FIG. 5 with the balloons inflated.

[0039]FIG. 7 is a cutaway side view of the distal portion of theablation catheter of FIG. 5 with the balloons inflated.

[0040]FIG. 8 is a cutaway, side view of the distal portion of theablation catheter with the balloons inflated, showing an alternativeembodiment for the location of the balloon openings in the first, outerballoon.

[0041]FIG. 9 is a cutaway, perspective view of an alternative embodimentof the ablation catheter of FIG. 7, wherein a ring electrode replacesthe coil electrode.

[0042]FIG. 10 is a cutaway, side view of the distal portion of thealternative embodiment of the ablation catheter of FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0043] A typical human heart includes a right ventricle, a right atrium,a left ventricle and a left atrium. The right atrium is in fluidcommunication with the superior vena cava and the inferior vena cava.The atrioventricular septum separates the right atrium from the rightventricle. The tricuspid valve contained within the atrioventricularseptum provides communication between the right atrium and the rightventricle. On the inner wall of the right atrium where it is connectedwith the left atrium is a thin walled, recessed portion, the fossaovalis. A drawing of a human heart with the left atrium (11) and theopenings (os) into the respective pulmonary veins (14) is shown in FIG.1.

[0044] In a normal heart, contraction and relaxation of the heart muscle(myocardium) takes place in an organized fashion as electrochemicalsignals pass sequentially through the myocardium from the sinoatrial(SA) node to the atrioventricular (AV) node and then along a welldefined route which includes the His-Purkinje system into the left andright ventricles. Initial electrical impulses are generated at the SAnode and conducted to the AV node. The AV node lies near the ostium ofthe coronary sinus in the interatrial septum in the right atrium. TheHis-Purkinje system begins at the AV node and follows along themembranous interatrial septum toward the tricuspid valve through theatrioventricular septum and into the membranous interventricular septum.At about the middle of the interventricular septum, the His-Purkinjesystem splits into right and left branches which straddle the summit ofthe muscular part of the interventricular septum.

[0045] Sometimes abnormal rhythms occur in the atria which are referredto as atrial arrhythmia. Three of the most common arrhythmia are ectopicatrial tachycardia, atrial fibrillation and atrial flutter. Atrialfibrillation can result in significant patient discomfort and even deathbecause of a number of associated problems, including: (1) an irregularheart rate which causes the patient discomfort and anxiety, (2) loss ofsynchronous atrioventricular contractions which compromises cardiachemodynamics resulting in varying levels of congestive heart failure,and (3) stasis of blood flow, which increases the vulnerability of thepatient to thromboembolism.

[0046] Efforts to alleviate these problems have included significantusage of pharmacological treatments and occasionally surgicalprocedures. It has been discovered that similar success can be achievedwithout invasive surgery by ablation procedures performed within theatria as disclosed in U.S. Pat. No. 5,575,766. To accomplish thisnon-invasive procedure successfully, the ablation catheter must bepositioned at pre-determined locations within the right and left atriato ablate predetermined tracks, thus forming a natural barrier to theformation of reentry circuits.

[0047] The specific pathological cause for atrial fibrillation is notwell understood. It has been surprisingly discovered that one source foratrial premature contractions which may cause atrial fibrillation,particularly paroxysmal atrial fibrillation, originates in the pulmonaryveins associated with the left atrium of the heart.

[0048] In order to understand the structure of the medical devices ofthe invention, the medical procedure for their use within the heart mustfirst be understood. In use, the medical device (10) of the presentinvention is advanced into the left atrium (11) and is then introducedinto the appropriate pulmonary vein (14) or os of that pulmonary vein asshown in FIGS. 2 and 2A. (It is understood that ablation procedures maybe necessary in more than one of the pulmonary veins. However, forpurposes of discussion of the invention, the process will be limited tomedical procedures performed in a single pulmonary vein.) Once in place,the ablation catheter (12) creates a lesion which electrically isolatesthe source of the atrial premature contraction in the pulmonary vein(14) from connection with the left atrium (11).

[0049] The pulmonary veins (14) are generally tubular in structure,increasing in size as they open into the left atrium (11). It has beendiscovered that the conduction of atrial premature contraction through apulmonary vein (14) into the left atrium (11) can be completely haltedby formation of a circumferential ablation lesion around the pulmonaryvein (14), or in some circumstances around the os of the pulmonary vein,at a location proximal from the source of the atrial prematurecontraction. Merely ablating a single point on the surface of thepulmonary vein (14), which is perceived to be the source of thepremature atrial contraction, may not be sufficient to isolate thesource of the atrial premature contraction from the left atrium (11).

[0050] It is also important that the medical practitioner be able tomonitor the electrical activity of the pulmonary vein (14) both beforeand after the ablation procedure is complete to assure that the sourceof atrial premature contraction has been successfully isolated from theleft atrium (11).

[0051] Conventional procedures for ablation within the heart generallyutilize either a conventional tip electrode or one or more ringelectrodes on an ablation catheter. To effectively and efficientlyablate tissue, these electrodes are relatively small in diameter,usually in the range of about 5 French to about 8 French (1 Frenchequals one-third millimeter (0.039 in.)). Because the diameter of apulmonary vein (14) may be as large as about 20 millimeters (0.79 in.),it is impractical to use a conventional ablation electrode on aconventional ablation catheter to form the circumferential lesion aroundthe inside of a pulmonary vein (14).

[0052] The steps of the process in one embodiment of the presentinvention for the formation of a circumferential ablation lesion withina pulmonary vein (14) include introducing into a pulmonary vein (14), orinto the os of the pulmonary vein, an ablation catheter (12) containinga pair of balloons (20, 22), one located within the other, to preventthe flow of blood through the pulmonary vein (14) as shown in FIGS. 2and 2A. The ablation catheter (12) also includes an ablating system forablating tissue, which system is secured to the catheter (12) butlocated inside the pair of balloons (20, 22). Finally the tissue withinthe pulmonary vein (14), or the os of the pulmonary vein, is ablated ata location proximal to the source of the atrial premature contraction toform a circumferential lesion.

[0053] In a first preferred embodiment the medical device (10) includesthe catheter (12) onto which the first balloon (20) and the secondballoon (22) are secured as shown in FIGS. 2-9. The catheter (12) of thefirst embodiment of the present invention contains a proximal end (16)and a distal end (18) as shown in FIGS. 3 and 5. The composition of thecatheter (12) is conventional and should be sufficiently pliable topermit the catheter (12) to be advanced through the vasculature into theheart, across the chambers of the heart and ultimately into thepulmonary vein (14). While the distal portion of the catheter (12) maybe more pliable than the remaining portion of the catheter (12), thepliability of the catheter (12) may also be consistent throughout thelength of the catheter (12). An increase in pliability can be achievedthrough conventional procedures well known in the industry. To assist inthe advancement of the catheter (12) through the vasculature and throughthe chambers of the heart, the main portion of the catheter (12) may bestiffer and less pliable than the distal portion of the catheter (12).In one embodiment, this main portion can be formed of any conventionalcatheter material having shape memory or permitting distortion from andsubsequent substantial return to its desired shape. This main portionmay also be reinforced, for example, by use of a reinforcing braid orother such suitable strand material having high temporal strength. Theenhanced pliability of the distal portion of the catheter can beachieved by a number of methods well known in the industry, includingthe use of a fused flexible tip catheter or a soft tipped cathetercomprised of the same or similar materials with similar performancecharacteristics as are present in the reinforced portion of the catheter(12). In addition, a more pliable distal portion of the catheter (12)can be created through modifications made in the catheter (12) such asby additional drawing of the catheter body to reduce the thickness ofthe walls, thus achieving enhanced pliability.

[0054] The overall length of the catheter (12) should be about 50 toabout 150 cm. (20 to about 60 in.)

[0055] The catheter (12) preferably also contains a plurality ofconventional lumens which extend from the proximal end (16) of thecatheter to or near the distal end (18) of the catheter (12). In onepreferred embodiment, the catheter (12) includes at least four separatelumens. The first lumen extends from the proximal end (16) to the distalend (18) of the catheter (12) and ends in a distal opening (32) in thedistal end (18) of the catheter (12). This lumen is designed toaccommodate a guidewire that passes through the catheter (12) duringintroduction of the catheter (12) into the pulmonary vein (14). Thislumen may also be used for the introduction of a contrast media into thepulmonary vein (14) at a location distal from the balloons (20, 22) ofthe catheter (12) during the ablation procedure. A second lumen in thecatheter (12) receives electrode conductor wires which pass from theproximal end (16) of the catheter to an electrode (30) or electrodeslocated near the distal end (18) of the catheter (12). The third lumenis designed for introduction of a conductive media into the second,inner balloon (22). This media is utilized to inflate the second, innerballoon (22). For the introduction of media at this location, openings(24) are provided in the catheter (12) at a location within the second,inner balloon (22) as shown in FIGS. 6 and 7. The fourth lumen isdesigned for the introduction of a conductive media, preferably a salinesolution, into the first, outer balloon (20). Media introductionopenings (26) are provided in the catheter (12), preferably bothproximal and distal from the second inner balloon (22), but inside thefirst balloon (20) as shown in FIGS. 6 and 7 to receive this conductivemedia. This conductive media is designed to conduct energy from theelectrodes (30) secured to the catheter (12) through the balloonopenings (28) in the surface (34) of the outer balloon (22) to contactthe inner surface of the pulmonary veins (14). Additional lumens may beprovided in the catheter (12) for other conventional utilizations.

[0056] The invention also includes an introducing system to introduceconductive media into the space within the first, outer balloon (20),and an ablating system secured to the outside surface (13) of thecatheter (12) at a location within the first balloon (20), but outsideof the second balloon (22). Other components may also be secured to thecatheter (12) to assist in the formation of circumferential ablationlesions, including, for example sensors (not shown) to sense thepresence of premature atrial contractions, temperature sensors (notshown) to sense the temperature of the tissue being ablated, markers(not shown) to mark the location of the catheter (12) and its componentswithin the pulmonary vein (14) and other conventional componentsnormally utilized with an ablation catheter (12).

[0057] The two balloons (20, 22) are secured to the outer surface (13)of the catheter (12) as shown in FIGS. 3-8. The first, outer balloon(20) typically measures from about 10 mm (0.4 in.) to about 100 mm (4.0in.) in length and when inflated generally conforms to an ellipsoidshape as shown in FIGS. 5, 6 and 7. The maximum diameter of the first,outer balloon (20) when fully inflated is variable up to about 60 mm(2.4 in.). The second, inner balloon (22) is also secured to the outersurface (13) of the catheter (12) at a location within the first, outerballoon (20) as shown in FIGS. 5, 6 and 7. When inflated, the second,inner balloon (22) measures approximately 2 mm (0.1 in.) to about 100 mm(4.0 in.) in length, preferably 5 mm (0.2 in.) to about 20 mm (0.8 in.),with approximately the same diameter as the first outer balloon (20).Preferably, inflation of the second, inner balloon (22) also inflatesthe first, outer balloon (20) and maintains the outer balloon (20) inthat inflated position throughout the ablation procedure as shown inFIGS. 5, 6 and 7.

[0058] The balloons (20, 22) are manufactured according to conventionaltechnology from materials such as a flexible or thermoplastic rubber,urethane, latex, cellulose or other conventional materials and aresecured to the catheter (12) conventionally.

[0059] Inflation of the balloons (20, 22) is accomplished usingconventional methods, preferably using a radiopaque contrast solution,and more preferably a marked saline solution. In addition, if desired,radiopaque marker bands (not shown) may be secured to the surface (34)of the first, outer balloon (20) to mark its relative position in thepulmonary vein (14). Once the proper location in the pulmonary vein(14), or the os of the pulmonary vein, is determined, the catheter (12)may be withdrawn slightly from that location so that the subsequentlyformed circumferential ablation lesion will be located proximal from thesource of the premature atrial contraction.

[0060] The balloons (20, 22) when properly inflated should preventcompletely the flow of blood through the pulmonary vein (14) around theballoons (20, 22). The balloons (20, 22) are preferably inflated byintroduction of media through openings (24) within second, inner balloon(22) which inflates both the inner balloon (22) and the outer balloon(20). Alternatively, or additionally, additional media may be introducedthrough the media introduction openings (26) in the catheter (12) insidethe outer balloon (20) to assist in its inflation. In order to assurethat the balloons (20, 22) form a tight seal in the pulmonary vein (14),a contrast media may be injected through the distal opening (32) locatedin the distal tip (18) of the catheter (12). If any leaks arediscovered, additional media may be introduced into the inner balloon(22) until the balloons (20, 22) completely stop the flow of blood inthe pulmonary vein (14).

[0061] Once the balloons (20, 22) are properly inflated, conductivemedia is introduced into the outer balloon (22) through the mediaintroduction openings (26) in the outer surface (13) of the catheter(12) located proximal and distal from the second, inner balloon (22).Preferably, two such media introduction openings (26) are provided inthe catheter (12), both proximal and distal from the second, innerballoon (22) as shown in FIGS. 6 and 7. In one embodiment, theconductive media is a saline solution marked with markers so that it canbe monitored by fluoroscopy, although any appropriate conductive mediamay be used.

[0062] Balloon openings (28) are provided in the surface (34) of thefirst, outer balloon (20) as shown, for example, in FIGS. 6 and 7. In apreferred embodiment, these balloon openings (28) are formed in a seriesof lines passing around the surface (34) of the first, outer balloon(20). These balloon openings (28) may be formed in a single line, or ina preferred embodiment, they form two or more lines, each runningcompletely around the surface (34) of the first, outer balloon (20) asshown in FIGS. 6 and 7.

[0063] In an alternative embodiment, these lines of balloon openings(28) are located only distal from the second inner balloon (22) in thefirst outer balloon (20) as shown in FIG. 8. This alternative structurepermits the conductive media to be concentrated distal from the innerballoon (22) within the pulmonary vein (14) against the surface of thetissue and not be dissipated into the left atrium (11).

[0064] The electrodes (30), located within the first, outer balloon(20), but outside of the second inner balloon (22), preferably emitradiofrequency energy, which is conducted by the conductive mediathrough the balloon openings (28) in the surface (34) of the first outerballoon (20) to the tissue within the pulmonary vein (14) Because theseballoon openings (28) are formed in a line or lines around the surface(34) of the first, outer balloon (20), the conductive energy emitted bythe electrodes (30) forms a circumferential lesion inside the pulmonaryvein (14).

[0065] While the preferred source for the ablation energy isradiofrequency energy, other sources of energy may be utilized, such asmicrowave, ultrasound or heat. During the ablation process, the energyfrom the catheter (12) is conducted by the conductive media to thetissue within the pulmonary vein (14). In a preferred embodiment, theimpedance of the conductive media should be less than the impedance ofthe human tissue so that the tissue will heat up to an ablationtemperature at a faster rate than does the media.

[0066] The ablating system can consist of a pair of coil electrodes (30)as shown in FIGS. 6 and 7 or, alternatively, ring electrodes (130) asshown in FIGS. 9 and 10. In a preferred embodiment two electrodes,either coil (30) or ring (130), are secured to the catheter (12), oneproximal and one distal from the inner balloon (22), but both inside theouter balloon (20).

[0067] In order to monitor the formation of the ablation lesion, atemperature sensor (not shown), such as a thermistor or thermocouple canalso be secured to the outer surface (13) of the catheter (12). Sensingelectrodes (not shown) can also be secured to the catheter (12) at anyappropriate location to monitor electrical activity in the pulmonaryvein.

[0068] In operation, a modified Seldinger technique is normally used forthe insertion of the medical device (10) into the body. Using thisprocedure, a small skin incision is made at the appropriate location tofacilitate catheter or dilator passage. Subcutaneous tissue is thendissected, followed by a puncture of the vessel with an appropriateneedle with a stylet positioned at a relatively shallow angle. Theneedle is then partially withdrawn and reinserted at a slightlydifferent angle into the vessel making sure that the needle remainswithin the vessel. The soft flexible tip of an appropriate sizeguidewire is then inserted through, and a short distance beyond, theneedle into the vessel. Firmly holding the guidewire in place, theneedle is removed, leaving a portion of the guidewire exposed outside ofthe vessel. The guidewire is then advanced into the right femoral veinand through the inferior vena cava into the right atrium. (The preferredprocedure uses the inferior approach to the right and left atria.Procedures for the retrograde and superior approach to the left atriumcan also be used and are within the scope of the invention.) With theguidewire in place, a dilator is then passed over the guidewire with anintroducer. The dilator and introducer generally form an assembly to beadvanced together along the guidewire into the inferior vena cava. Theintroducer may be a conventional straight introducer or, preferably, aprecurved introducer, such as the SL2 introducer sold by DaigCorporation.

[0069] A Brockenbrough needle or trocar is then inserted through thelumen of the dilator to the right atrium to be used to create an openingthrough the interatrial septum, preferably at the fossa ovalis. Theentire assembly (dilator, introducer and Brockenbrough needle) passesthrough the vena cava into the right atrium so that the tip restsagainst the interatrial septum at the level of the fossa ovalis. TheBrockenbrough needle is then advanced through the fossa ovalis. Afterthe opening is made through the interatrial septum, the Brockenbroughneedle is exchanged for a guidewire. The dilator, guidewire and guidingintroducer for the left atrium are then advanced into the left atrium.The dilator is then removed leaving the introducer and guidewire inplace in the left atrium. The ablation catheter (12) is then advancedthrough the lumen of the introducer over the guidewire and into the leftatrium. The guidewire is then maneuvered until it enters the appropriatepulmonary vein (14). The catheter (12) is then advanced over theguidewire into the pulmonary vein and the guidewire is removed.

[0070] Once the distal end (16) of the ablation catheter (12) has beenadvanced into the pulmonary vein (14), it may be positioned by use of asensing electrode (not shown) secured at or near the distal end (16) ofthe catheter (12). This sensing tip electrode senses electrical activitywithin the pulmonary vein (14), including atrial premature contractions.Once the source of the atrial premature contractions has been confirmedto be distal to the inner balloon (22) and outer balloon (20), the innerballoon (22) is inflated by introducing media through the mediaintroduction openings (26) in the catheter (12). By inflating the innerballoon (22), the outer balloon (20) is also inflated. This innerballoon (22) and outer balloon (20) must be sufficiently inflated toprevent completely the flow of blood through the pulmonary vein (14)around the balloons (20, 22) To assure that no blood flows around theballoons (20, 22), marked media may be injected into the pulmonary vein(14) at a point distal from the balloons (20, 22), for example, throughthe opening (32) in the distal tip (18) of the catheter (12). Anyleakage around the balloons (20, 22) can then be determined byfluoroscopy and eliminated by additional pressure on the inside of theinner balloon (22).

[0071] The ablating system, preferably a pair of Rf coil electrodes(30), or ring electrodes (130), which are secured to the outer surface(13) of the catheter (12) at a location within the outer balloon (20)and outside of the inflated inner balloon (22), then emit energy whichis conducted by the conductive media through the balloon openings (28)in the surface (34) of the outer balloon (20) to the surface of thetissue in the pulmonary vein (14). Sufficient energy is emitted tocreate a circumferential lesion of sufficient width and depth to blockcompletely the passage of the atrial premature contractions through thepulmonary vein (14). The temperature of the tissue of the pulmonary vein(14) may be monitored by temperature sensors, such as thermistors orthermocouples (not shown), located on the surface (13) of the catheter(12) outside the balloons (20, 22). In addition, sensing electrodes (notshown) may be located proximal from the balloons (20, 22) to senseelectrical activity through the vessel after the ablation procedure hasbeen completed to assure complete blockage of the pulmonary vein (14).The tissue to be ablated may be at any location within the pulmonaryvein (14) or in the os of the pulmonary vein (14).

[0072] After the ablation procedure has been completed and tested by useof sensing electrodes, each of the elements of the system are removedfrom the pulmonary vein (14) and left atrium (11). If desired,additional sensing devices can be introduced into the left atrium (11)to determine whether there are any other sources for the atrialpremature contractions in other pulmonary veins (14).

[0073] It will be apparent from the foregoing that while particularforms of the invention have been illustrated and described, variousmodifications can be made without departing from the spirit and scope ofthe invention. For example, the present invention could also be used forablation procedures in other vessels such as the coronary sinus andother veins.

We claim:
 24. A medical device for ablation of tissue associated with avessel connected to a human heart comprising an ablation catheter, afirst, outer balloon, secured to the catheter and capable of forming aseal to at least partially restrict the flow of blood within the vesselat a location associated with the vessel, a second, inner balloon,secured to the catheter at a location within the first outer balloon, anintroduction system operating in conjunction with the catheter tointroduce a conductive media inside the medical device, an ablatingelement secured to the catheter, and a plurality of balloon openingsprovided in the first, outer balloon.
 25. The medical device of claim 24wherein the ablating element comprises a ring electrode.
 26. The medicaldevice of claim 24 wherein the ablating element comprises a coilelectrode.
 27. The medical device of claim 24 wherein the introductionsystem comprises a lumen which extends through the catheter into a mediaintroduction opening in the catheter located within the first outerballoon.
 28. The medical device of claim 24 wherein the plurality ofballoon openings are provided in a line in an outside surface of thefirst, outer balloon.
 29. The medical device of claim 28 wherein theballoon openings extend around a circumference of the first, outerballoon.
 30. The medical device of claim 29 wherein the balloon openingsare located on a distal portion of the first, outer balloon.
 31. Themedical device of claim 25 wherein the ring electrode is secured to thecatheter at a location within the outer balloon.
 32. The medical deviceof claim 26 wherein the coil electrode is secured to the catheter at alocation within the outer balloon.
 33. The medical device of claim 24further comprising a lumen in the catheter including a distal opening inthe catheter, which distal opening is located distal from the first andsecond balloons.
 34. The medical device of claim 25 wherein the ringelectrode emits radiofrequency energy.
 35. The medical device of claim26 wherein the coil electrode emits radiofrequency energy.
 36. Themedical device of claim 24 wherein the conductive media is a conductivesaline solution.
 37. A medical device for ablation of tissue associatewith a vessel connected to a human heart comprising an introducer with aproximal and a distal end and a lumen passing through the introducerfrom its proximal to its distal end, an ablation catheter, capable ofbeing inserted within the lumen of the introducer to at least partiallyrestrict the flow of blood within the vessel, a first, outer balloon,secured to the catheter, a second, inner balloon, secured to thecatheter at a location within the first outer balloon, an introductionsystem operating in conjunction with the catheter within the first outerballoon, an ablating element secured to the catheter, and a plurality ofballoon openings provided in the first outer balloon.
 38. The medicaldevice of claim 37 wherein the ablating element comprises a ringelectrode.
 39. The medical device of claim 37 wherein the ablatingelement comprises a coil electrode.
 40. The medical device of claim 37further comprising a plurality of balloon openings provided in a line inan outside surface of the first outer balloon.
 41. The medical device ofclaim 40 wherein the balloon openings extend around a circumference ofthe first, outer balloon.
 42. The medical device of claim 40 wherein theballoon openings are located on a distal portion of the first, outerballoon.
 43. The medical device of claim 38 wherein the ring electrodeis secured to the catheter at a location within the outer balloon. 44.The medical device of claim 39 wherein the coil electrode is secured tothe catheter at a location within the outer balloon.
 45. A process forablation of tissue associated with a vessel of a human heart comprisingintroducing an ablation catheter to a position adjacent to tissueassociated with the vessel, wherein the ablation catheter comprises anextended catheter, a first, outer balloon, and a second, inner balloonalso secured to the catheter, at least partially sealing the vessel torestrict at least partially the flow of blood through the vessel,passing a conductive media through balloon openings in the first outerballoon, conducting energy from an electrode secured to the catheter byuse of the conductive media through the balloon openings in the outerballoon to the tissue, and ablating the tissue to form an ablationlesion.